1. Field of Invention
The present invention relates to a method of ecological restoration, and more particularly to a method of ecological restoration of water bodies containing excess nutrient, comprising a step of putting an organism that can eat blue-green algae in the water body polluted by the blue-green algae, so that an eco-system of the water body containing excess nutrients is restored.
2. Description of Related Arts
Many human producing activities discharge waste water rich in nitrogen and phosphorus to the rivers, lakes and so on. Under this situation, the self-purification capacity of water bodies is destroyed, and the nutrient s such as nitrogen and phosphorus accumulate and finally result in an outburst of unicellular algae, especially blue-green algae, in the water body. The blue-green algae are mainly aeruginosa. An overrun of the blue-green algae seriously pollutes the water bodies.
Most of the cells of blue-green algae have a developed algin layer, and are fully covered by a thick amylase substance. These algin and amylase are hardly digested by the digestant enzyme of any present organism, especially higher animals. Therefore, the emergence of the blue-green algae can not become part of food chain in the ecosystem. Domestic and overseas experts in environmental protection and biology try to use higher animals including fish to control the pollution caused by blue-green algae, but have not got ideal results.
Doubtlessly, adding chemical herbicide and flocculants in the water can kill the blue-green algae instantly. Chemical method is the easiest method to solve the problem, but the chemical and the catabolite finally run up to human bodies via the food chains. What's more important is that chemical treatment can not fundamentally solve this problem of eutrophication. Once the chemicals are decomposed and diluted, the algae will propagate again, and a constant chemical treatment is required.
When dissolved oxygen in water is high in value, the phosphate always crystallizes and becomes a chemical form; when dissolved oxygen in water is low in value, the phosphate will be dissolved in the water, so that charging gas to increase the oxygen content in water can reduce the solubility of phosphate so as to restrain the propagation of algae. In the process of the comprehensive biological management of the water containing excess nutrient, increasing oxygen to water is very helpful. However, only increasing oxygen can not solve the problem of eutrophication in water, the propagation of the algae is still inevitable for the nutrient recycle in the long run.
Microbiological preparation can improve the microbes in the water and substrate silt, and decompose and mineralize the organic matter and nutrient s, so as to stabilize some nutrient s in inertia form temporarily. The result is similar to the method of increasing oxygen. It is worth mentioning that the living of the microbes depends on the environment and demands absolute dominate populations. Generally, the microbe method may keep good operation status for 15-30 days. Once the conditions change, including climate, substrate, and various water qualities: dissolved oxygen, PH value, temperature and so on, more microbes need to be added continually, or outburst of blue-green algae may be more serious.
The algae have abundant nutrition and can decompose quickly, so that they are fine organic fertilizer. However, from the commercial perspective, the cost of fetching the algae is much higher than the algae being the organic fertilizer.
As we all know, aquatic plants, such as hyacinth, aquatic peanut, aquatic lotus, aquatic vegetables and aquatic flowers, do absorb nutrient in water, however they also cover the surface of lakes and blot out sunshine, which will lead some living creatures under water and silt, especially some deepwater plants to die, and what's more, will lead the nutrient in the silt to dissolve. Therefore, the disadvantages brought by aquatic plant far exceed the advantages.